High quality audio power amplifiers are traditionally large, heavy, and inefficient. Typically, these audio power amplifiers are capable of high power audio output with low total harmonic distortion. However, the traditional audio power amplifiers may achieve only approximately 25% efficiency under normal audio operating conditions because such audio power amplifiers generally use inefficient linear or quasi-linear amplifiers (e.g., Class A, B, G, and/or H amplifiers).
Recently, the demand for more efficient audio power amplifiers has increased. Thus, audio power amplifiers have started to include Class D amplifiers. Class D amplifiers allow audio power amplifiers to achieve higher efficiency than traditional audio power amplifiers because switches in the Class D amplifiers are not operated in the linear region. However, a Class D amplifier can introduce ripple content at an input to an inner loop of the Class D amplifier that can increase undesirable signal distortion.